December 19, 2013

COLUMBUS, Ohio – A tomato-rich diet could help protect at-risk postmenopausal women from breast cancer, according to new research from The Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute (OSUCCC – James).

Breast cancer risk among postmenopausal women increases as body mass index climbs. This study suggested that eating a diet high in tomatoes had beneficial effects on the level of a hormone (adiponectin) known to play a role in regulating fat and sugar metabolism. Prior observational studies have shown that higher adiponectin levels are associated with reduced risk of breast cancer. This new study was published in The Endocrine Society's Journal of Clinical Endocrinology & Metabolism.

Studies have investigated specific dietary patterns as a strategy for obesity-related breast cancer prevention among high-risk postmenopausal women, but few have examined associations between tomato- and soy-enriched diets and markers of breast cancer prevention.

This new longitudinal study examined the effects of both tomato-rich and soy-rich diets in a group of 70 postmenopausal women considered at increased risk of breast cancer due to family history of the disease and/or being overweight or obese.

For 10 weeks, women in the study ate tomato products containing at least 25 milligrams of lycopene daily. For a separate 10-week period, the participants consumed at least 40 grams of soy protein daily. Before each test period began, the women were instructed to abstain from eating both tomato and soy products for two weeks.

Researchers examined levels of adiponectin, a hormone involved in regulating blood sugar and fat levels associated with breast cancer risk in epidemiology studies, before and after women completed the soy and tomatoes parts of the study.

“After the tomato-rich diet, participants' serum adiponectin levels climbed to nine percent. The effect was slightly stronger in women who had a lower body mass index. Based on these data, we believe regular consumption of at least the daily recommended servings of lycopene-containing fruits and vegetables would promote breast cancer prevention in a population at risk for breast cancer,” said the study's first author, Adana Llanos, PhD, MPH.

Llanos was a postdoctoral fellow at The OSUCCC – James when she conducted this research and now serves as an assistant professor of epidemiology at Rutgers University School of Public Health and a researcher at Rutgers Cancer Institute of New Jersey.

"The findings demonstrate the importance of obesity prevention," Llanos said. "Consuming a diet rich in tomatoes had a larger impact on adiponectin levels in women who maintained a healthy weight."

“We currently understand that nutrients found in tomatoes are associated with lower breast cancer risk. We also know that higher levels of adiponectin are associated with lower risk. The current research effectively connects the dots between tomatoes and adiponectin and helps us further understand at least one way that tomatoes might reduce breast cancer,” adds Jessica Krok, PhD, second author on the paper and post-doctoral fellow at The OSUCCC-James. “It is important for breast cancer patients to know that this research does not address how or if tomatoes improve prognosis among women diagnosed with this disease.”

The soy diet was linked to a reduction in study participants' adiponectin levels. Researchers originally theorized that a diet containing large amounts of soy could be part of the reason that Asian women have lower rates of breast cancer than women in the United States, but any beneficial effect may be limited to certain ethnic groups, researchers said.

This research was supported by grants from the Breast Cancer Research Foundation and The Ohio State University Clinical and Translational Science Award (NIH/NCRR UL1-RR025755). Electra Paskett, PhD, associate director of population sciences at The OSUCCC – James, served as principal investigator of the study.

About The OSUCCC – James
The Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute strives to create a cancer-free world by integrating scientific research with excellence in education and patient-centered care, a strategy that leads to better methods of prevention, detection and treatment. Ohio State is one of only 41 National Cancer Institute (NCI)-designated Comprehensive Cancer Centers and one of only four in the United States funded by the NCI to conduct both phase I and phase II clinical trials. The NCI recently rated Ohio State’s cancer program as “exceptional,” the highest rating given by NCI survey teams. As the cancer program’s 228-bed adult patient-care component, The James is a “Top Hospital” as named by the Leapfrog Group and one of the top cancer hospitals in the nation as ranked by U.S.News & World Report.

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